In general, microcontact printing is a “soft lithography” process which involves the application of coating in the form of small structures (e.g., submicron patterns) to substrates. Such structures are useful in a variety of fields including chemistry, biology, and semiconductor and integrated circuit processing. For example, in the fields of chemistry and biology, microcontact printing is useful in forming micropatterns for drug and cellular measurement.
There are a variety of approaches to microcontact printing. In one conventional approach, a conventional microcontact printing apparatus includes a support structure for holding a microcontact printing stamp, a platform (e.g., a vacuum chuck) for holding a substrate, and an air-actuated piston for moving the platform and the substrate toward the microcontact printing stamp. A variable-pressure chamber contains the support structure, the platform, and the piston. Additionally, a vacuum pump connects to both the variable-pressure chamber and the platform. The microcontact printing stamp typically includes rigidly supported elastomeric material such as polydimethylsiloxane (PDMS) which defines a stamping surface having a pattern (e.g., a combination of contact surfaces and recesses) which is transferable to the surface of the substrate.
During operation, a user inks (i.e., wets) the microcontact printing stamp with a stamping material which can be suitable for forming a self-assembled monolayer (SAM) on the surface of the substrate. An example of such a liquid is a hexadecanethiol-based solution. Next, the user manually maneuvers the microcontact printing stamp so that the stamping surface of the microcontact printing stamp is visually parallel to the substrate surface. The user manually actuates the air-actuated piston in order to move the substrate, which is held to the platform by the vacuum, into contact with the microcontact printing stamp.